Socket wrenches are extremely valuable tools because such wrenches have interchangeable sockets that mount upon a driving stub of a socket wrench head, and each socket makes a snug sliding fit upon a polygonal head of a rotatable threaded fastener which may be either a bolt or a nut. Such sockets may be used with any of several fastener driving tools which include a socket wrench as above stated, or a pneumatic nut driver, or a screwdriver type hand tool which has a shaft with a socket at the end.
Interchangeable sockets for fastener driving tools have been known for many years, and the principal objection to them is that a different socket is required for each different size of threaded fastener; and that drawback is greatly increased in the United States of America because of the continued use of English unit fasteners concurrently with the adoption of metric unit fasteners. The result is that at the present time a socket wrench set to fit all fasteners from about 1/4" to about 2" requires an inordinate number of sockets.
There have been a variety of approaches to the idea of providing an adjustable socket. Those known to applicant that are believed to be most pertinent to the present application are those of applicant's own U.S. Pat. No. 4,520,698, that issued June 4, 1985, and two of the nineteen patents that were cited against that patent. Those are Conway U.S. Pat. No. 2,850,931, issued Sept. 9, 1951, and Werich U.S. Pat. No. 2,555,836, issued June 5, 1951.